i. Field of the Invention
This invention relates to a multi-purpose pryometallurgical process enhancing device for delivering at least one fluid to the interior of a metallurgical furnace; more especially the invention is concerned with such a device which will function as an oxygen lance and as an oxy-fuel burner.
ii. Description of the Prior Art
Electric arc furnaces are increasingly employed in the manufacture of steel, and the use of oxy-fuel burners to provide a source of auxiliary heat in electric arc furnaces is also common. Oxy-fuel burners are employed in electric arc furnaces to increase the total heat input to a low power furnace; to heat up the cold spots, particularly in a high power furnace so as to promote uniform melting; and to offset the effects of maximum demand control on electricity supplies.
The location of the oxy-fuel burners is determined by the need to avoid other fittings on the furnace shell. Conventionally the burners are mounted on a carriage by means of which they are inserted into the furnace through the furnace wall and retracted from the furnace, the burner axis being inclined downwardly to direct the burner nozzle towards the molten contents.
With conventional oxy-fuel burners the burner axis is typically inclined at an angle of up to about 30.degree. to the horizontal axis of the furnace. Furthermore, in order that the burner flame not contact the centrally disposed carbon electrodes, and in order to obtain the desired distance between the metal melt and the burner nozzle, the burners do not enter or enter only a very short distance into the furnace, in the vicinity of the furnace wall and in a lower part of the furnace wall.
It is also customary to employ an oxygen lance in the refining of steel in a direct arc Electric Arc Furnace, especially to reduce the carbon content of the steel. Typically, in an Electric Arc Furnace, the oxygen lance is introduced through the side wall, for example, through the furnace slag door and the longitudinal axis of the lance is inclined to the horizontal. The optimum disposition of an oxygen lance is a vertical position whereby the jet of oxygen, typically delivered at supersonic velocity, is directed vertically downwardly towards the melt. In existing designs of Electric Arc Furnace, however, it is not practical to introduce the oxygen lance vertically downwardly through the roof because of the necessary length of the lance body, the roof support and the electrode support structures located above the roof, which occupy much of the space above the roof.
It has been suggested in U.S. Pat. No. 3,197,539 to introduce oxy-fuel burners through the roof of an Electric Arc Furnace but this proposal has not been exploited commercially in view of the lack of free space above the roof of an Electric Arc Furnace for mounting of the burners, their support structures and oxygen and fuel lines.
Steel is also produced in a top blown BOF (Basic Oxygen Furnace) process. In such a furnace oxygen is introduced vertically downwardly towards the molten metal through the roof of the furnace through a large oxygen lance; this lance is long and cumbersome and requires heavy support structures to raise and lower it.
Both the top blown BOF and the direct arc steel making Electric Arc Furnace employ a charge which includes a major amount of scrap which initially occupies a much greater volume of the furnace than after it has been melted.
Oxy-fuel burners and oxygen lances are typically employed at different stages of the treatment in an Electric Arc Furnace and have conventionally been separate items of equipment with their own support structures.
The nozzle of oxy-fuel burners of known design, has a limited life and in conventional practice when the nozzle is degraded or burnt out, the nozzle end or tip is cut away and a new end or tip is welded in its place, thus representing complicated and costly maintenance.